1. Field of the Invention
The present invention relates to an organic light emitting display device, and more particularly to an organic light emitting display device having pixels of which operation reliability is secured by incident light.
2. Description of the Related Art
Recently, various flat panel display devices having reduced weight and volume as compared with cathode ray tube display devices, have been developed. Among others, an organic light emitting display device using organic compounds as light emitting materials has excellent brightness and color purity. As a result, the organic light emitting display device has been spotlighted as a next generation display device. Further, the organic light emitting display device is thin and light and is also able to be driven by using a relatively low power so that the organic light emitting display device has been expected to be useful in a portable display device or the like.
The portable display device is exposed to various external circumstances so that the visibility of a video image displayed by the portable display device may vary according to the various external circumstances, in particular, according to the external light illumination. In order to prevent this, there has been contrived a method to sense the intensity of the external light by having a light sensor disposed inside the portable display device and thus to control the brightness of a pixel unit.
Therefore, the organic light emitting display device used as a portable display device has a pixel unit allowing the brightness thereof to be controlled by the intensity of the external light. The pixel unit includes a pixel circuit having a transistor on a substrate and an organic light emitting diode receiving an electric current from the pixel circuit to emit light. A light sensor is formed in a region where the pixel circuit and the organic light emitting diode are not formed.
In the organic light emitting display device constructed as above, if an internal light, that is, the light generated by the organic light emitting diode, shines upon the pixel circuit, an electrical current may be undesirably generated by the internal light in the transistor or the like, and mal-function may occur.